Multi-component compatible data architecture

ABSTRACT

A backbone network, comprising a first switch comprising a first port configured to communicate a data stream via an Ethernet interface, and a second port configured to communicate the data stream via a SONET/SDH interface, and a second switch comprising a third port configured to receive the data stream from the first switch via the Ethernet interface, wherein the first switch and the second switch are synchronized.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/737,803 filed Apr. 20, 2007, U.S. Pat. No. 7,675,945 andentitled “Multi-Component Compatible Data Architecture”, which claimsthe benefit of U.S. Provisional Application Ser. No. 60/826,764 filedSep. 25, 2006 and entitled “System for TDM Data Transport Over EthernetInterfaces,” U.S. Provisional Application Ser. No. 60/857,741 filed Nov.8, 2006 and entitled “TDM Data Transport Over Ethernet,” and U.S.Provisional Application Ser. No. 60/886,833 filed Jan. 26, 2007 andentitled “Closed Loop Clock Synchronization,” all of which are by SergeF. Fourcand and are incorporated herein by reference as if reproduced intheir entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

Ethernet is the preferred protocol for many types of networks because itis flexible, decentralized, and scalable. Ethernet is flexible in thatit allows variable-sized data packets to be transported across differenttypes of mediums using various nodes each having different transmissionspeeds. Ethernet is decentralized in that it allows the end devices totransmit and receive data without oversight or intervention from acentralized server or party. Furthermore, Ethernet is scalable in thatit can be implemented in both small-scale and large-scale networks.These advantages make Ethernet a preferred choice for data distributionin many computer networks.

Unfortunately, Ethernet does have some drawbacks. When Ethernet packetsare transported through the network, the Ethernet packets contend withother traffic being transported over the same links or through the samenodes. The contentious traffic not only comprises packets bound for thesame destination, but also packets bound for other destinations that aretransported over the same link or through the same node as the Ethernetpacket. This contention produces burstiness and jitter at the nodeswithin the network. Some of these problems can be addressed by usingresource arbitration and buffers at the nodes, and by prioritizing thepackets into high priority data and low priority data. However, thesesolutions increase network complexity, increase delay, and detract fromthe inherent advantages of Ethernet.

The aforementioned drawbacks are part of the reason Ethernet has notbeen widely implemented in networks carrying time division multiplexed(TDM) data. Specifically, Ethernet does not provide a sufficient Qualityof Service (QoS) to meet the stringent jitter and data loss requirementsfor voice traffic in the public switched telephone network (PSTN) andother TDM networks. Instead, TDM traffic is carried by highlysynchronized networks, such as synchronous optical networks (SONET) andsynchronous digital hierarch (SDH) networks. Various Ethernetenhancements, such as circuit emulation, provider backbone transport,and pseudowires, have been proposed to address the jitter and data lossissues, but these enhancements fail to couple the flexibility ofEthernet with the high QoS requirements of TDM networks. Thus, a needexists for an improved Ethernet protocol that is flexible, easy toimplement, supports the QoS requirements of TDM networks, and iscompatible with existing technology.

SUMMARY

In one aspect, the disclosure includes a backbone network, comprising afirst switch comprising a first port configured to communicate a datastream via an Ethernet interface, and a second port configured tocommunicate the data stream via a SONET/SDH interface, and a secondswitch comprising a third port configured to receive the data streamfrom the first switch via the Ethernet interface, wherein the firstswitch and the second switch are synchronized.

In another aspect, the disclosure includes a network componentcomprising a first port configured to communicate a first data streamover an Ethernet interface, the first data stream comprising a firstEthernet packet data and a first time division multiplexed data, asecond port configured to communicate a second data stream over aSONET/SDH interface, the second data stream comprising a second Ethernetpacket data and a second time division multiplexed data, a switchingfabric coupled to the first port and the second port and configured tocommunicate at least some the first data stream and the second datastream between the first port and the second port, wherein the Ethernetpacket data and the time division multiplexed data are not encapsulated.

In a third aspect, the disclosure includes a network comprising a firstline card configured to send a data stream via an Ethernet interface,wherein the data stream comprises an Ethernet packet data and a timedivision multiplexed data, a second line card configured to receive thedata stream via the Ethernet interface, a third line card configured tosend the data stream via a SONET/SDH interface, and a fourth line cardconfigured to receive the data stream via the SONET/SDH interface,wherein the first line card, the second line card, the third line card,and the fourth line card are synchronized to an absolute time.

These and other features will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is an illustration of an embodiment of an Ethernet MAC frame.

FIG. 2 is an illustration of an embodiment of an Ethernet data stream.

FIG. 3 is an illustration of an embodiment of an H-TDM overlaysynchronous timeslot scheme.

FIG. 4 is an illustration of an exemplary layout of timeslots of theH-TDM overlay synchronous timeslot scheme.

FIG. 5 is an illustration of the partitioning of the H-TDM overlaysynchronous timeslot scheme using the H-JUMBO operational mode.

FIG. 6A is an illustration of an 8B encoding scheme.

FIG. 6B is an illustration of a plurality of TDM octets encoded usingthe 8B encoding scheme.

FIG. 7A is an illustration of a 7B encoding scheme.

FIG. 7B is an illustration of a plurality of HPF octets encoded usingthe 7B encoding scheme.

FIG. 8A is an illustration of a 9B encoding scheme.

FIG. 8B is an illustration of a plurality of BEP octets encoded usingthe 8B encoding scheme.

FIG. 9 is an illustration of an exemplary data stream combining the 7Band 9B encoding schemes.

FIG. 10 is an illustration of an exemplary block diagram of amulti-transport switch.

FIG. 11 is an illustration of an exemplary block diagram of anothermulti-transport switch.

FIG. 12 is an illustration of an exemplary block diagram of a line cardthat is implemented on the multi-transport switch of FIG. 11.

FIG. 13 is an illustration of an exemplary block diagram of abuffer/groomer.

FIG. 14 is an illustration of an exemplary block diagram of amulti-transport switch.

FIG. 15 is an illustration of an exemplary block diagram of a line cardthat is implemented on the multi-transport switch of FIG. 14.

FIG. 16 is an illustration of an exemplary block diagram of anothermulti-transport switch.

FIG. 17 is an illustration of an exemplary block diagram of anothermulti-transport switch.

FIG. 18 is an illustration of an exemplary block diagram of a line cardthat is implemented by the multi-transport switches of FIG. 16 or 17.

FIG. 19 is an illustration of an exemplary block diagram of another linecard that is implemented by the multi-transport switches of FIG. 16 or17.

FIG. 20 is an illustration of an exemplary block diagram of another linecard that is implemented by the multi-transport switches of FIG. 16 or17.

FIG. 21 is an illustration of an exemplary unified network.

FIG. 22 is an illustration of an exemplary network architecture.

FIG. 23 is an illustration of one embodiment of a general-purposecomputer system suitable for implementing the several embodiments of thedisclosure.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

Disclosed herein is a unified network architecture that may transportvoice, video, and data services across various types of networks. Theunified network architecture comprises a plurality of multi-transportswitches that communicate time division multiplexed (TDM) data andpacket data over both Ethernet and SONET/SDH links without encapsulatingthe data. Specifically, the multi-transport switches may communicate theTDM and packet data using a plurality of operational modes. Themulti-transport switches may also communicate with both Ethernet andSONET/SDH switches to establish at least one synchronous communicationpath.

The operational modes disclosed herein comprise a Huawei synchronized(H-SYNC) mode, a Huawei time division multiplexed (H-TDM) mode, and aHuawei jumbo (H-JUMBO) mode. The H-SYNC mode synchronizes Ethernet nodesby including synchronization and timestamp information in aninter-packet gap. The H-TDM mode defines an overlay synchronous timeslotscheme that transports octet-sized timeslots within a predefinedsynchronization window. The timeslots may carry synchronization data,timestamp data, control data, and payload data, where the payload datamay comprise TDM data, high performance flow (HPF) data, and/orbest-effort packet (BEP) data. The overlay synchronous timeslot schememay allow data to be efficiently mapped between Ethernet nodes andSONET/SDH nodes without encapsulating the data. The H-JUMBO mode maypartition the H-TDM data stream into a plurality of sections, andencapsulate each section into an Ethernet packet that may be processedby Ethernet nodes that do not support the H-TDM operational mode.

FIG. 1 illustrates one embodiment of an Ethernet packet 100. The packet100 begins with a preamble 104, which may be about seven octets of arepeated pattern, such as “10101010.” The preamble 104 may allow anode's physical layer signaling (PLS) circuitry to reach steady-statesynchronization with the packet's timing. The preamble 104 may befollowed by a start of frame delimiter (SFD) 106, which may be a singleoctet with the pattern “10101011,” and may be used to indicate thebeginning of the packet 100. The destination address (DA) 108 mayspecify the address of the destination node for which the packet 100 isintended, and may be about six octets. The source address (SA) 110 mayspecify the address of the source node from which the packet 100originated, and may be about six octets. The packet 100 may contain aplurality of optional octets 112 that are used to associate the packet100 with a type protocol identifier (TPID) and/or a virtual local areanetwork identifier (VID). For example, up to about sixteen octets may beused for associating the packet 100 with a TPID and a VID, for exampleas described in IEEE 802.1Q.

The packet 100 continues with a length/type field 114, which may specifythe length of the payload 116 and the Ethernet protocol being used, andmay be about two octets. The payload 116 may be a variable-sized fieldthat carries a data payload. Although the payload 116 may contain anyamount of data, in specific embodiments the payload 116 may contain fromabout 42 octets to about 1,500 octets in standard packets, and maycontain from about 9,000 octets to about 12,000 octets in jumbo packets.The frame check sequence (FCS) 118 may be used for error detection, andmay be a four-octet field that contains a cyclic redundancy check (CRC)value calculated using the contents of the packet 100. Although not partof the packet 100, the inter-packet gap (IPG) 102 may be data or idlecharacters that separate the packets 100. The IPG 102 may contain abouttwelve octets of idle control characters, although any amount of data oridle characters may be used in the IPG 102.

As illustrated in FIG. 2, a synchronous timestamp (Sync) 202 may beinserted in the IPG 102 between two Ethernet packets 204. The Sync 202may be used to synchronize an upstream node's clock with a downstreamnode's clock in the H-Sync operational mode. Specifically, the Sync 202may be a four-octet packet that synchronizes the two clocks infrequency, but does not necessarily align the clocks in phase. The Sync202 may also indicate the beginning of a synchronization window having apredetermined period, such as about 125 microseconds (μs). The Sync 202need not be located in every IPG 102, but in some embodiments, it may beadvantageous to have at least one Sync 202 during every synchronizationwindow.

In some embodiments, there are advantages to inserting the timestamp inthe IPG 102. For example, the H-Sync timestamp does not affect theavailable bandwidth because the Sync 202 is located in the IPG 102,which is an idle period in standard Ethernet communications. Further,communicating the timestamp in the IPG 102, rather than within thepacket 100, allows the timestamp to be transmitted independent of thepacket 100. The independent transmission of the Sync 202 and the packet100 ensures that the timestamp will not become stale, and allows theupstream and downstream nodes' clocks to be synchronized withouttransmitting multiple timestamps from the upstream node to thedownstream node. Similarly, upon receiving the timestamp at a downstreamnode, the timestamp may be extracted and processed without processingthe packet 100.

FIG. 3 depicts one embodiment of the overlay synchronous timeslot schemeof the H-TDM operational mode. Specifically, FIG. 3 illustrates anoverlay synchronous timeslot scheme within a synchronization windowhaving a predefined period, such as about 125 microseconds (μs). Theoverlay synchronous timeslot scheme comprises the SFD 304, the Sync 306,a timeslot map (TS Map) 308, and a payload 310. The SFD 304 maydelineate a beginning of the H-TDM frame, and may be a reserved Ethernetcontrol symbol, such as the /K28.1/control symbol. As persons ofordinary skill in the art will recognize, the /K28.1/control symbolcomprises a comma that may be used to enable 8 bit/10 bit (8B/10B)symbol synchronization when the overlay synchronous timeslot scheme iscommunicated on 8B/10B encoded media. In an embodiment, the SFD 304 mayalso specify the size of the H-TDM frame.

The Sync 306 may be used to initiate the synchronization windows,synchronize the synchronization windows, and phase-align thesynchronization windows between two nodes. The Sync 306 may comprise aforward timestamp that indicates the transmission time of the Sync 306.The Sync 306 may also comprise a loop-back timestamp, the composition ofwhich varies depending on whether the Sync 306 is being transmitted froman upstream node or a downstream node. Specifically, the loop-backtimestamp may comprise a calculated one-way transmission delay when theSync 306 is being transmitted from the upstream node. Alternatively, theloop-back timestamp may comprise a calculated internal processing delayand a synchronization reference when the Sync 306 is being transmittedfrom the downstream node. A detailed description of the Sync 306, thefrequency-synchronization process, and the phase-alignment process isfound in U.S. patent application Ser. No. 11/735,590 entitled“Inter-Packet Gap Network Clock Synchronization.”

The overlay synchronous timeslot scheme may continue with the TS Map308, which may specify the type and location of the data in the payload310. In one embodiment, the individual timeslots in the payload 310 maybe assigned to TDM, HPF, and BEP traffic according to a predefinedpattern. For example, the first one thousand timeslots may be assignedto TDM traffic, the subsequent five thousand timeslots may be assignedto HPF traffic, and the subsequent three thousand timeslots may beassigned to BEP traffic. In such an embodiment, the TS Map 308 may beomitted from the H-TDM frame if the nodes are aware of the predefinedpattern. Alternatively, the TS Map 308 may indicate the assignment ofeach timeslot in the payload 310 as a TDM, a HPF, or a BEP timeslot.Using the TS Map 308, TDM, HPF, and BEP traffic may be dynamicallyinterleaved within the overlay synchronous timeslot scheme.

Some timeslots at the beginning and/or end of the synchronization windowmay be part of a guard interval 302. The guard intervals 302 allow theH-TDM frame to float within the synchronization window. Specifically,the location of SFD 304 in relation to the beginning of thesynchronization window may vary between synchronization windows. Assuch, the guard interval 302 at the beginning of the synchronizationwindow may be the same or a different size than the guard interval 302at the end of the synchronization window, and the size of the guardintervals 302 in one synchronization window may vary from the size ofthe guard intervals 302 in other synchronization windows. Such anembodiment may be advantageous because the integrity of the SFD 304,Sync 306, TS Map 308, and the data in the payload 310 is maintained ifany of the data in the guard intervals 302 is dropped, corrupted, lost,or otherwise unreadable, for example, due to clock tolerances or othernon-deterministic factors. In some embodiments, the guard interval 302may transport low priority BEP data. Alternatively, the guard interval302 may be zero-padded or may contain idle characters.

Although the synchronization window may be any duration, there areparticular advantages to using a synchronization window with a period ofabout 125 μs. Specifically, synchronizing the overlay synchronoustimeslot schemes to a 125 μs synchronization window allows the Ethernetnodes to be interoperable with the PSTN, SONET, SDH, and other TDMnetworks. As such, when the overlay synchronous timeslot scheme has a125 μs synchronization window, SONET/SDH transport overhead 312 may beadded to the overlay synchronous timeslot scheme format shown in FIG. 3.The SONET/SDH transport overhead 312 allows the data in the payload 310to be mapped between Ethernet networks and the SONET/SDH networks usedby the PSTN. The SONET/SDH transport overhead 312 is depicted assurrounding the Sync 306 because the Sync 306 may be inserted intovarious undefined octets of the SONET/SDH transport overhead 312. In anembodiment, the SONET/SDH transport overhead 312 may be omitted from theoverlay synchronous timeslot scheme, such that the Sync 306 may belocated between the SFD 304 and the TS Map 308.

The overlay synchronous timeslot scheme may allow the H-TDM frame totransport a variety of data types. When the synchronization window has aperiod of about 125 μs and each timeslot carries an octet of data, eachof the timeslots in the overlay synchronous timeslot scheme represents asingle channel with about 64 kilobits per second (Kbps) of bandwidth.These channels provide sufficient bandwidth to carry a voiceconversation compatible with the PSTN. Thus, voice channels that arecarried in an H-TDM frame may be referred to as TDM data.

The overlay synchronous timeslot scheme also provides octet-sizedgranularity that supports the communication of other traffic withstringent QoS requirements, referred to herein as HPF data. In anembodiment, the HPF data may require a deterministic amount ofbandwidth. Examples of HPF traffic comprise video, audio, and othermultimedia traffic. HPF traffic may be assigned multiple channels withsingle-octet granularity according to the bandwidth requirements of theHPF traffic. In other words, each channel assigned to a HPF increasesthe bandwidth allocated to the HPF by 64 Kbps. For example, a lowresolution streaming video HPF requiring about 256 Kbps of bandwidth maybe assigned about four channels from the H-TDM frame. Similarly, a HPFrequiring about 3.2 megabits per second (Mbps) of bandwidth may beassigned about fifty channels from the H-TDM frame. The deterministicallocation of bandwidth may allow the HPFs to be transmitted withoutinterruptions or delays within the HPF data stream. In such a case, abackpressure signaling system may not be required. In an embodiment,HPFs may be allocated bandwidth in 576 Kbps granularity to correspond toan entire column of a SONET/SDH frame.

In addition to being assigned to carry TDM and HPF data, the timeslotsin the payload 310 may be assigned to carry BEP data. The BEP data maycomprise low priority Ethernet packet data, data downloads, webbrowsing, or any other low priority data. In an embodiment, anytimeslots in the payload 310 that are not assigned as TDM or HPFtimeslots are automatically assigned as BEP timeslots. In anotherembodiment, at least a portion of the timeslots are assigned as BEPtimeslots to ensure that at least some BEP data is contained in eachH-TDM frame.

While the allocation of bandwidth may be performed as described abovefor constant bit rate (CBR) data streams, variable bit rate (VBR) datastreams present an additional challenge. In an embodiment, VBR datastreams may be allocated bandwidth according to a maximum amount ofbandwidth that the VBR data streams may use. Consider a case wherein theVBR HPF may be a Motion Picture Experts Group (MPEG) encoded video datastream. The MPEG format may encode video data such that less bandwidthis needed to display scenes with few changes or movement, and morebandwidth is needed to display scenes with a lot of changes or movement.In such a case, a HPF carrying the MPEG encoded video data may beallocated a sufficient quantity of timeslots to transport the maximumamount of bandwidth that the MPEG encoded video data stream willrequire. During scenes where less than the maximum amount of bandwidthis being used to communicate the MPEG encoded video data stream, theunused bandwidth may be reused by other data types, as described indetail below.

FIG. 4 illustrates a more detailed layout of the overlay synchronoustimeslot scheme from FIG. 3. FIG. 4 contains three rows of information:an internal synchronization signal 402 that delineates thesynchronization window, a timeline 404 that enumerates each timeslot,and a descriptor 406 that describes the data that may be containedwithin each timeslot. The internal synchronization signal 402 maycorrespond to the synchronization window established when initiating theH-Sync or H-TDM operational modes, as described in U.S. patentapplication Ser. No. 11/735,590 entitled “Inter-Packet Gap Network ClockSynchronization.”

The synchronization window may begin at timeslot 0. Timeslots 0 throughX represent the guard intervals 302, and thus the descriptor 406indicates that BEP traffic may be transported during these timeslots.Specifically, timeslot X−1 comprises a first part of a first BEP,identified as BEP A. At timeslot X, BEP A may be interrupted by the SFD304 that may delineate the beginning of the H-TDM frame. If the H-TDMframe comprises SONET/SDH overhead 312, as shown in FIG. 3, then theSONET/SDH overhead 312 and the Sync 306 are communicated subsequent tothe SFD 302, e.g. in timeslots X+1 through X+W. In one embodiment, atleast one idle octet or SONET/SDH overhead 312 octet may be insertedbetween timeslots X+1 and X+W. Such octets enable efficient mapping ofthe Sync 306 to an SONET/SDH frame, such that the Sync 306 aligns withthe columns of the SONET/SDH frame. The TS Map 308 may follow timeslotX+W, and may indicate the type and location of the HPF, TDM, and/or BEPtimeslots in the payload 310. The TS Map 308 may extend through timeslotX+Y.

The payload 310 of the H-TDM frame follows timeslot X+Y. The payload 310may contain a second part of BEP A, which may be interrupted by at leastone timeslot of TDM or HPF data. Upon the completion of the TDM or HPFtimeslots, BEP A may continue until BEP A terminates at timeslot J.Following an IPG or immediately following the end of BEP A, a second BEPidentified as BEP B may be initiated in timeslot K and the remainingtimeslots. The H-TDM frame may end at timeslot N, however BEP B maycontinue into the guard interval 302, and perhaps into the guardinterval 302 of the subsequent synchronization window. Thus, thetransmission of a BEP does not necessarily end at the end of the H-TDMframe or at the end of the synchronization window, but instead when theBEP is complete or when interrupted by the subsequent SFD 304.

While the timeslot layout depicted in FIG. 3 communicates two BEPs, anyamount of BEP data may be communicated within the synchronizationwindow. For example, the synchronization window may contain no BEP data,part of a BEP, exactly one BEP, or multiple BEPs. Further, while FIG. 4illustrates that the BEP data is interrupted only once due to a seriesof TDM and/or HPF timeslots, persons of ordinary skill in the art willappreciate that the BEP data may be interrupted any number of times byany number of TDM or HPF timeslots, or by timeslots assigned to adifferent instance of BEP data, as described below.

FIG. 5 illustrates an example of the H-TDM overlay synchronous timeslotscheme partitioned using the H-JUMBO operational mode. As describedabove, the H-JUMBO operational mode partitions the overlay synchronoustimeslot scheme into sections that are encapsulated into Ethernetframes. The sections may not necessarily correspond to any particularcontent within the overlay synchronous timeslot scheme, but rather maybe selected based on the quantity of the octets. While any size may beselected, in specific embodiments each section may be sized to fit intothe standard Ethernet frame payloads, which are between about 42 octetsand about 1,500 octets, or jumbo Ethernet frame payloads, which are morethan 1,500 octets, e.g. between about 9,000 octets and about 12,000octets. In another specific embodiment, jumbo Ethernet frames with apayload of about 9,600 octets are used in the H-JUMBO operational mode.

As shown in FIG. 5, each section of the H-TDM overlay synchronoustimeslot scheme may be inserted into a jumbo payload 504 that may beencapsulated within Ethernet Layer 2 framing 502. The Ethernet Layer 2framing 502 allows the H-TDM overlay synchronous timeslot scheme to betransported by standard Ethernet nodes, e.g. nodes that do not supportthe H-SYNC or H-TDM operational modes. The Ethernet layer 2 framing 502may then be removed, and the H-TDM overlay synchronous timeslot schememay be reassembled and transported as before. In an embodiment, optionalVIDs and/or TPIDs may be comprised in the jumbo Ethernet frames 506 toassist in reordering the received packets. In another embodiment, thejumbo Ethernet frames 506 may be transported in series to ensure properordering. When implementing a 10 Gigabits per second (Gbps) Ethernetinterface and a payload of about 9,600 octets for each of the jumboEthernet frames 506, the H-TDM overlay synchronous timeslot scheme maybe encapsulated within about sixteen jumbo Ethernet frames 506. Fewerjumbo frames may be required when implementing Gigabit Ethernetinterfaces.

As mentioned above, the H-TDM overlay synchronous timeslot scheme may becommunicated over both Ethernet and SONET/SDH interfaces withoutencapsulation. Specifically, SONET/SDH frames may be communicated overinterfaces without embedded signaling, whereas Ethernet packets may becommunicated over interfaces using an under-laying Ethernet Layer 1embedded signaling protocol. To accommodate the differences between theEthernet and SONET/SDH interfaces, some data manipulation may occur.Specifically, each timeslot in the H-TDM overlay synchronous timeslotscheme may be encoded with signaling in accordance with the data typeassigned to the timeslot and the type of interface over which the datais transported, as described in detail below.

FIG. 6A illustrates an embodiment of an eight-bit (8B) data encodingscheme that may be used for timeslots assigned to carry TDM data. The 8Bencoding scheme places exactly one TDM byte, e.g. bits D0 through D7, ineach timeslot that is assigned to carry TDM data. Using all eight bitsof the octet for TDM data does not leave any space for embeddedsignaling. However, the TDM data does not require any embeddingsignaling because the eight-bit bytes used by the PSTN already containembedded signaling, and thus there is no need to add additionalsignaling to the TDM data. Such a one-to-one correlation between the TDMbytes and the 8B-encoded octets may be particularly beneficial whencommunicating the overlay synchronous timeslot scheme over SONET/SDHinterfaces.

FIG. 6B illustrates an example of the correlation between a TDM datastream and the 8B-encoded TDM timeslots. The TDM data stream comprisesOctet 1 through Octet N, where each octet carries eight data bits, D0through D7. As described above, each timeslot of the H-TDM overlaytimeslot scheme also carries eight bits of data. As such, the eight bitsof Octet 1 may be carried in the eight bits of TDM timeslot 1, the eightbits of Octet 2 may be carried in the eight bits of TDM timeslot 2, andthe eight bits of Octet 3 may be carried in the eight bits of TDMtimeslot 3. Consequently, each octet in the TDM data stream may becarried in its entirety in one of the timeslots assigned to carry TDMdata.

FIG. 7A illustrates an embodiment of a 7 bit/8 bit (7B) data encodingscheme for timeslots assigned to carry HPF data. The 7B encoding schemeplaces seven bits of an eight-bit HPF byte in each timeslot that isassigned to carry HPF data. Using only seven bits of the octet for HPFdata leaves one bit available for embedded signaling, which is referredto as the 7B signaling bit. The 7B encoding scheme may be particularlybeneficial when communicating the HPF data in the overlay synchronoustimeslot scheme over SONET/SDH interfaces.

The 7B signaling bit may indicate whether the HPF timeslot is active oridle. For example, when the 7B signaling bit has a “1” value, the HPFtimeslot may be active and the data carried in the HPF timeslot may beHPF data. When the 7B signaling bit has a “0” value, the HPF timeslotmay be idle and the HPF timeslot may carry other data types. Persons ofordinary skill in the art will recognize that the values used toindicate whether a HPF timeslot is active or idle are arbitrary, andthat a zero value may just as easily be used to indicate the HPFtimeslot is active. In addition, the position of the 7B signaling bitmay be fixed as the first bit of every HPF timeslot. Alternatively, the7B signaling bit may be in any other location or the location may vary.

When the HPF timeslots carry HPF data, the beginning and end of the HPFdata may be indicated by a transition of the 7B signaling bit betweenthe idle state and the active state. For example, if an HPF timeslot isidle, e.g. has its 7B signaling bit set to zero, and a subsequent HPFtimeslot is active, e.g. has its 7B signaling bit set to one, then thesubsequent timeslot may contain the beginning of the HPF data. In suchan embodiment, the HPF data may be shifted to the beginning of the HPFtimeslot. In other words, the HPF data may begin immediately after the7B signaling bit. Alternatively, if an HPF timeslot is active, e.g. hasits 7B signaling bit set to one, and a subsequent HPF timeslot is idle,e.g. has its 7B signaling bit set to zero, then the subsequent timeslotmay contain the end of the HPF data. When the HPF data ends, theremainder of the HPF timeslot may be filled with zeros or otherwisepadded. Alternatively, the HPF timeslot may proceed to other data, suchas BEP data.

When the 7B encoding scheme is implemented, the capacity of the HPFtimeslots may be less than the capacity of the original networkinterface. Specifically, the use of one of the eight bits as a signalingbit may equate to about 14 percent overhead per octet. Thus, about 86percent of the HPF timeslots may be used to carry data when using the 7Bencoding scheme. If each timeslot in the H-TDM overlay timeslot schemeprovides about 64 kbps of bandwidth and the timeslots are assigned toeach data type on a SONET/SDH column basis, then each SONET/SDH columnrepresents about 576 kbps of bandwidth. As such, each SONET/SDH frameassigned to carry HPF data may have a maximum bandwidth of about 504kbps when implementing the 7B encoding scheme described herein. Such areduction in data transport capacity is comparable to the data capacityreduction that is experienced when Ethernet packets are encapsulated inSONET/SDH frames. In other words, the bandwidth consumed by the 7Bsignaling bit is about equal to the bandwidth consumed by the preamble,the start of frame delimiter, the IPGs, and/or any other non-datacarrying portions of the Ethernet data stream that are encapsulated intothe SONET/SDH frames.

In addition to signaling, the 7B signaling bit allows the bandwidth tobe dynamically reused when there is no HPF data. Specifically, when the7B signaling bit indicates that the HPF timeslot is idle, the sevendata-carrying bits of the HPF timeslot may be immediately reused tocarry other data, such as BEP data. Conversely, when the 7B signalingbit indicates that the HPF timeslot is active, the seven data-carryingbits of the HPF timeslot may be immediately used to carry HPF data, e.g.without waiting for the BEP or other data to be completed. Theinstantaneous switching of traffic types means that no additional HPFbuffering may be needed when reusing the HPF channels for other traffictypes.

The reuse of the HPF timeslots by the BEP traffic does not affect theswitching of the synchronous transport signal (STS) switch fabric. In anembodiment, BEP data may be switched using a standard Ethernet switchingfabric, whereas TDM and HPF data may be switched using a standardSONET/SDH STS switching fabric. U.S. patent application Ser. No.11/735,591, entitled “Multiplexed Data Stream Payload Format,” providesa detailed disclosure of the demultiplexing of the H-TDM data stream. Bythe time the H-TDM data stream reaches the point where the TDM and HPFtraffic are separated from the BEP traffic, it may be possible that somesupervision and/or framing information, such as that contained inSDH/SONET overhead 312, has already been added to the stream, andtherefore would have to be regenerated if the stream going to the TDMswitch fabric is altered.

There are many switching options for the data in the idle HPF timeslots.If the reuse of idle HPF timeslots occurs before the data reaches theSTS switch fabric, then the data reusing the HPF timeslot may beforwarded to the TDM switch fabric where it may be switched as if itwere provisioned for the HPF channel. This extraneous switched data maylater be added to the BEP data or discarded as it leaves the STS switchfabric. Alternatively, the data reusing the HPF timeslot may beforwarded to the Ethernet switching fabric to be switched as normal BEPdata. In such a case, a fixed value may be inserted in the idle HPFtimeslots to replace the BEP traffic when the BEP traffic is extracted.In some of these cases, supervision and/or framing information may haveto be regenerated. If the reuse occurs after the data passes through theSTS switch fabric, the data reusing the HPF timeslot may be selectedfrom the BEP data egress on the Ethernet switch fabric or an egressbuffer that stores the BEP data that is output on the Ethernet switchfabric.

FIG. 7B illustrates an example of the correlation between a HPF datastream and the 7B-encoded HPF timeslots. The HPF data stream comprisesOctet 1 through Octet N, with each octet carrying eight data bits, D0through D7. In contrast with the TDM timeslots shown in FIG. 6B, the 7Bencoding scheme does not provide sufficient bandwidth for each HPFtimeslot to carry an entire HPF octet. Consequently, the eight data bitsof each of the HPF octets may be bit shifted into the seven availablebits in each HPF timeslot. For example, HPF Timeslot 1 comprises the 7Bsignaling bit in the first bit and data bits D0 through D6 from HPFOctet 1 in the remaining bits. Similarly, HPF Timeslot 2 comprises the7B signaling bit in the first bit, and data bit D7 from HPF Octet 1 anddata bits D0 through D5 from HPF Octet 2 in the remaining bits. Finally,HPF Timeslot 3 comprises the 7B signaling bit in the first bit, and databits D6 through D7 from HPF Octet 2 and data bits D0 through D4 from HPFOctet 3 in the remaining bits.

FIG. 8A illustrates an embodiment of an 8 bit/9 bit (9B) encoding schemethat may be used for BEP data. The 9B encoding scheme comprises a singlesignaling bit and eight bits of BEP data. Using nine bits allows the 9Bencoding scheme to contain signaling information and an entire octet ofBEP data. The 9B encoding scheme may be particularly useful when the BEPdata is transported over a SONET/SDH interface.

The beginning and end of a BEP may be indicated by the transition of thesignaling bit. In an embodiment, the transition of the 9B signaling bitfrom a zero to a one may indicate the beginning of a new BEP, whereasthe transition of the 9B signaling bit from a one to a zero may indicatethe end of the BEP. Persons of ordinary skill in the art will recognizethat the transitions of the 9B signaling bit from one to zero toindicate the end of the BEP is arbitrary, and that the transition from aone to a zero may be used to indicate the beginning of the BEP. When aBEP terminates in a BEP timeslot or in a reused HPF timeslot, theremainder of the BEP timeslot or reused HPF timeslot may be filled withzeros or otherwise padded. The subsequent BEP timeslots or reused HPFtimeslots, including the 9B signaling bit, may also be filled with zerosor padded until a new BEP is detected. When the new BEP is detected, thenew BEP may begin in the first available bit of the first available BEPtimeslot or idle HPF timeslot.

In the 9B encoding scheme, the position of the 9B signaling bit may varywithin the BEP timeslots. Specifically, because the 9B signaling bit ispositioned in front of eight bits of BEP data and the BEP timeslotscontain eight bits, the position of the signaling bit may increment oneposition in each subsequent timeslot. For example, when three BEPtimeslots are adjacent to one another, the 9B signaling bit may belocated in the first bit in a first timeslot, in the second bit in thesecond timeslot, and in the third bit in a third timeslot. As such,every ninth BEP timeslot may lack a 9B signaling bit. In other words,the BEP timeslot may not contain a 9B signaling bit when the previousBEP timeslot contains the 9B signaling bit in the eighth bit of a BEPtimeslot.

FIG. 8B illustrates an example of the correlation between a BEP datastream and the 9B-encoded BEP timeslots. The BEP data stream comprisesOctet 1 through Octet N, with each octet carrying eight data bits, D0through D7. Using the 9B encoding scheme, each of the BEP octets may bepreceded by the signaling bit to generate the nine-bit segments. Becausethe BEP timeslots do not have enough bandwidth to carry all nine bits ineach BEP timeslot, the nine bits of each 9B-encoded segment may be bitshifted into the eight available bits in each BEP timeslot or into theseven available data bits in each idle HPF timeslot. For example, BEPTimeslot 1 contains the 9B signaling bit in the first bit and bits D0through D6 from BEP Octet 1 in the remaining bits. Similarly, BEPTimeslot 2 contains the bit D7 from Octet 1 in the first bit, the 9Bsignaling bit in the second bit, and bits D0 through D5 from BEP Octet 2in the remaining bits. Finally, BEP Timeslot 3 contains the bits D6 andD7 from Octet 2 in the first two bits, the 9B signaling bit in the thirdbit, and bits D0 through D4 from BEP Octet 3 in the remaining bits.

FIG. 9 illustrates an exemplary data stream depicting the variousproperties of the 7B encoding and 9B encoding schemes. Specifically,FIG. 9 illustrates a data stream organized into three SONET/SDH-likecolumns that are assigned to carry HPF data. Each of columns X, X+1, andX+2 comprise nine rows, row 1 through row 9, of data organized intoeight bit segments, bit 0 through bit 7 in each column. As persons ofordinary skill in the art will recognize, data is transported from theSONET/SDH frame on a row-by-row basis such that bits 0 through 7 ofcolumns X, X+1, and X+2 are serially communicated for row 1, then row 2,and so forth. As such, data that is not completed in column X continuesin the same row of column X+1, and data that is not completed in columnX+2 continues in the subsequent row of column X.

The eight bits of each row and column combination constitute the eightbits of an HPF timeslot. As such, each row of the three columns containsone HPF timeslot. When each of the three columns are assigned to carryHPF data and the 7B encoding scheme is implemented, the HPF timeslotsalign in the columns such that the first bit of each column is the 7Bsignaling bit. Specifically, bit 0 in all of the rows and for all threecolumns carries the 7B signaling bit, with a zero representing an idleHPF timeslot and a one representing an active HPF timeslot.

As shown in row 1, column X and column X+1 have the 7B signaling bit setto one, and thus indicate that HPF data is being transmitted. As shownin FIG. 9, the HPF data terminates at column X+1, row 1, bit 3, whereinthe remaining bits in column X+1, row 1 are zero-padded. The 7Bsignaling bits in the subsequent eight HPF timeslots are set to zero toindicate the HPF timeslots are idle. As such, the idle HPF timeslots maybe reused to carry BEP data.

When reusing the idle HPF timeslots, the transmission of a BEP mayresume at the bit where the BEP left off. As shown in column X+2, row 1,the transmission of the BEP resumes at bit 1 with the BEP data bit D4.The resumption of the BEP transmission at bit D4 assumes that the lastBEP data bit that was transmitted was BEP data bit D3, which would haveoccurred prior to column X. If no BEP data had been transmitted prior tocolumn X, then the 9B signaling bit would be in column X+2, row 1, bit 1with BEP data bits D0 through D5 following.

The HPF timeslots in rows 2 and 3 of the three columns and the HPFtimeslot in row 4 of column X are also idle, as indicated by the 7Bsignaling bit, e.g. bit 0, being set to zero in those timeslots. Assuch, BEP data may be placed in each of these idle HPF timeslots, forexample, using the 9B encoding scheme. As described above, the locationof the 9B signaling bit varies from timeslot to timeslot, and is shownin bold prior to the eight BEP data bits. While the 9B signaling bitremains at a one, the transmission of the BEP across the various columnscontinues. The end of the BEP may be indicated when the 9B signaling bittransitions to a zero, as shown in column X+2, row 2, bit 2.

Subsequent to the end of the BEP, there may be an idle period duringwhich there may be no HPF or BEP data to place in the HPF timeslots. Asshown in FIG. 9, a two octet idle period follows the end of the BEPwhere the bits are filled with zeros, including the 9B signaling bit.The zeros continue until a non-zero bit is detected, which may be thefirst signaling bit of a new BEP as shown in column X+1, row 3, bit 6.In some embodiments, BEP traffic resynchronization may be required, forexample at the beginning of a BEP or after a fault. In such cases, theresynchronization may be performed by detecting at least nineconsecutive zeros in the BEP traffic, not including the 7B signalingbits in reused HPF timeslots.

As shown in column X+2, row 3 and column X, row 4, the BEP datacontinues in the idle HPF timeslots. When new HPF data is available, the7B signaling bit is set to one and the BEP data may be interrupted. Asshown in column X+1, row 4, bit 0, a new HPF is indicated by the 7Bsignaling bit being set to one. Thus, column X+1, row 4 is an active HPFtimeslot and contains the new HPF data. Likewise, all subsequent HPFtimeslots shown in FIG. 9 also contain 7B signaling bits set to one, andthus also are active and contain HPF data.

Various alternative encoding schemes may also be used for the H-TDMoverlay synchronous timeslot scheme. For example, the H-TDM overlaysynchronous timeslot scheme may be communicated over various types ofEthernet interfaces using one of the underlying Ethernet Layer 1embedded signaling protocols. Specifically, the Ethernet interfaces mayhave 8B/10B encoded media or 64 bit/66 bit (64B/66B) encoded media. Whencommunicating the H-TDM overlay synchronous timeslot scheme over suchEthernet interfaces, the HPF and TDM timeslots may be superimposed ontop of BEP Ethernet data streams.

The 1000 BASE-X and 10G BASE-X Ethernet interfaces may use the 8B/10Bencoding scheme to communicate the H-TDM overlay synchronous timeslotscheme. In such embodiments, the beginning of an H-TDM frame may bedelineated using an Ethernet control symbol, such as the /K28.1/controlsymbol, and may be aligned to the 8B/10B symbols. Using the/K28.1/Ethernet control symbol allows the alignment of the H-TDM frameto be rapid and deterministic. Further, because each 8B/10B octet is astand-alone symbol and the physical layer Ethernet interfacesynchronizes itself to the 8B/10B symbols, no alignment may need to beperformed at then end of an H-TDM frame.

Each of the TDM, HPF, and BEP timeslots may be mapped to the 8B/10Bencoded media using 8B/10B encoding. The 8B/10B codes used forcommunicating the TDM and HPF timeslots may reflect the 8B/10B signalingused for data content, and the data carried in the TDM and HPF timeslotsmay be encoded using the 8B and 7B encoding schemes described above. The8B/10B codes used for communicating the BEP timeslots may reflect thenormal Ethernet Layer 1 packet encoding states. The mapping of TDM andHPF timeslots on 8B/10B encoded links may be done on a one-to-one basissuch that Ethernet octets may be delayed or replaced by the TDM and HPFtimeslots. As described above, the 7B encoding scheme may be used tocarry BEP data in the empty space in idle HPF timeslots. When a BEPpacket terminates, if a subsequent timeslot is a BEP timeslot, then theEnd of Packet Ethernet control symbol /K29.7/may be inserted todelineate the end of the BEP. If the subsequent timeslot is an idle HPFtimeslot, then the empty space of the idle HPF timeslot may bezero-padded to delineate the end of the BEP.

The 10G BASE-R and 10G BASE-W Ethernet interfaces may use 64B/66Bencoded media to communicate the H-TDM overlay synchronous timeslotscheme. When communicating the H-TDM overlay synchronous timeslot schemeover 10G BASE-R Ethernet interfaces, the beginning of the H-TDM framemay be delineated using an Ethernet control symbol, as described above.However, to minimize jitter due to alignment with the 64B/66B syncfields, a pointer may point to the beginning of the SONET/SDH transportoverhead 312, and may follow the Ethernet control symbol. The timeslotsbetween the pointer and the beginning of the SONET/SDH transportoverhead 312 may be used to communicate BEP data. The TDM, HPF, and BEPtimeslots communicated over 10G BASE-R Ethernet interfaces may map toSONET/SDH interfaces as described above, with the addition of the64B/66B sync fields between blocks of eight octets. Specifically, theTDM, HPF, and BEP timeslots may use the 8B, 7B, and 9B encoding schemes,respectively, to map the data to the SONET/SDH interfaces. Each of thesync fields may be set to ‘01’ to indicate data content whencommunicating the H-TDM timeslots.

While the H-SYNC, H-TDM, and H-JUMBO operational modes may be useful forcommunicating packet data and TDM data over any network, theseoperational modes may be particularly useful for communicating data overbackbone networks. As increasing numbers of voice, video, and dataservices are being offered to consumers, backbone networks may need tocommunicate packet-based data and TDM-based data efficiently andprecisely to support these services. The H-TDM operational mode not onlyenables communication of high priority TDM and HPF data and lowerpriority BEP data, but also lends itself for easy and efficient mappingbetween the major backbone network technologies, Ethernet and SONET/SDH.Further, the H-SYNC and H-JUMBO operational modes enable integration andbackwards compatibility with existing Ethernet and SONET/SDH backbonenetwork devices.

FIG. 10 illustrates an exemplary block diagram of a multi-transportswitch 1000 that communicates data across a backbone network using atleast one of the H-SYNC, H-TDM, and H-JUMBO operational modes. Themulti-transport switch 1000 comprises a plurality of Ethernet line cards1002, a plurality of SONET/SDH line cards 1004, and a switching fabric1006. The Ethernet line cards 1002 and the SONET/SDH line cards 1004 mayrepresent the ports on a node, and thus may communicate with similarEthernet line cards 1002 or SONET/SDH line cards 1004 on othermulti-transport switches 1000. The switching fabric 1006 may switch databetween two Ethernet line cards 1002, between two SONET/SDH line cards1004, or between one of the Ethernet line cards 1002 and one of theSONET/SDH line cards 1004. As such, the multi-transport switch 1000 canroute data from any of the line cards 1002, 1004 to any other of theline cards 1002, 1004. Various implementations of multi-transportswitches 1000 that support the H-SYNC, H-TDM, and H-JUMBO operationalmodes are shown in FIGS. 11-20 and are described below.

FIG. 11 illustrates an implementation of a multi-transport switch 1100that is compatible with legacy systems. The multi-transport switch 1100may be used to migrate existing networks towards a high-performanceSONET/SDH or Ethernet-based network. The multi-transport switch 1100comprises an SONET/SDH switch 1102, a virtual tributary (VT) switch1104, a column switch 1106, and an Ethernet switch 1108, which maycollectively be referred to as the switching fabric. In an embodiment,the SONET/SDH switch 1102 may be an existing STS-1 switching fabric, andmay switch the TDM and HPF traffic. The VT switch 1104 may be aconventional VT switch 1104, and may switch VT structures. Persons ofordinary skill in the art will recognize that VT structures are used fororganizing and transporting low rate sub-STS-1 synchronous signals. Thecolumn switch 1106 may switch the small granularity HPF traffic. TheEthernet switch 1108 may be any Ethernet switch that is suitable toswitch the BEP data. The SONET/SDH switch 1102 and the Ethernet switch1108 support both TDM data switching and packet switching in theirnative modes. While only one SONET/SDH switch 1102, one column switch1106, and one Ethernet switch 1108 is illustrated, it is contemplatedthat the multi-transport switch 1100 may contain a plurality ofSONET/SDH switches 1102, column switches 1106, and Ethernet switches1108.

The multi-transport switch 1100 may also comprise a TDM line card 1110and an Ethernet line card 1112. The TDM line card 1110 may exchange TDMdata with the SONET/SDH switch 1102 over any appropriatetelecommunications bus, such as a low voltage differential signaling(LVDS) bus. The Ethernet line card 1112 may exchange data with theSONET/SDH switch 1102 by encapsulating the data using any appropriateframing format. For example, Ethernet data may be encapsulated using thegeneric framing procedure (GFP) or the Link Access Procedure for SDH(LAPS).

The multi-transport switch 1100 may also comprise a plurality of H-TDMline cards 1114, 1116, 1118. The H-TDM line cards 1114, 1116, and 1118may support both legacy Ethernet and SONET/SDH communications, as wellas the operational modes described herein. Specifically, the H-TDM linecard 1114 may exchange data with other line cards over 64B/66B encodedmedia using any appropriate protocol, such as 10G BASE-R Ethernet, 10GBASE-W Ethernet, SONET STS-192c, or SDH VC-4-64c. Persons of ordinaryskill in the art will recognize that 10G BASE-W Ethernet encapsulatesEthernet data using the wide area network interface sublayer (WIS) intoa format compatible with the SONET STS-192c transmission format or theSDH VC-4-64c container. The H-TDM line card 1116 may statisticallymultiplex up to about ten one-gigabit (1G) 8B/10B Ethernet interfaces byadding a tag at the ingress of the H-TDM line card 1116. Similarly, theH-TDM line card 1118 may statistically multiplex up to about fourSTS-48c or VC-4-16c interfaces by adding a tag at the ingress of theH-TDM line card 1118. The H-TDM line cards 1114, 1116, and 1118 maycommunicate the TDM, HPF, and BEP traffic to the SONET/SDH switch 1102using the H-TDM synchronous timeslot scheme. The H-TDM line cards 1114,1116, 1118 may be coupled to the SONET/SDH switch 1102 using anyappropriate telecommunications bus, such as an LVDS bus. The H-TDM linecards 1114, 1116, 1118 may be coupled to the Ethernet switch 1108 usingany applicable communications bus, such as a 10-gigabit attachment unitinterface (XAUI) using 8B/10B signaling.

FIG. 12 illustrates an exemplary functional block diagram of an H-TDMline card 1200 that may be one of the H-TDM line cards 1114, 1116, or1118. The H-TDM line card 1200 may support both legacy communicationsand the operational modes described herein. The line card 1200 comprisesa reception path, indicated by the left to right arrows on the upperhalf of the H-TDM line card 1200, and a transmission path, indicated bythe right to left arrows on the lower half of the H-TDM line card 1200.Specifically, the reception path receives data from a communicationinterface (not shown), and transmits the data to the SONET/SDH switchand the Ethernet switch 1106 (shown in FIG. 11). Similarly, thetransmission path receives data from the SONET/SDH switch and theEthernet switch, and transmits the data to the communication interface.

Data on the reception path is received over the communication interfaceby physical layer circuits (PLS) 1202. As shown in line cards 1116 and1118 in FIG. 11, the PLS 1202 may receive data over a plurality ofdifferent communication interfaces. The line card 1200 may optionallycomprise an adaptor 1204 that supports statistical multiplexing ofmultiple interfaces as described above. As shown in FIG. 12 anddescribed below, data from the PLS 1202 or the adaptor 1204 may beprocessed along one of a plurality of paths depending on the type and/orformat of the data.

As shown at the top of the reception path, the data may be Ethernetpackets communicated in accordance with 10G Ethernet or synchronized 10GEthernet, such as through the H-SYNC operational mode, over an Ethernet,or SONET/SDH interface. When the Ethernet packets are received on theEthernet interface, the Ethernet packets may be sent to a 64B/66B to 9Bconverter 1208. When the Ethernet packets are received on the SONET/SDHinterface, the Ethernet packets may be encapsulated in a SONET/SDH framein accordance with the WIS. As such, the SONET/SDH encapsulated Ethernetpackets may be sent to a SONET/SDH descrambler 1210 and overheadprocessor 1214 to extract the Ethernet packets, which may then be sentto the 64B/66B to 9B converter 1208. The 64B/66B to 9B converter 1208may then send the Ethernet packet data to a data type demultiplexer1220, which is further described below.

The data received on the reception path may also comprise standardSONET/SDH frames or the H-TDM overlay synchronous timeslot schemecommunicated over a SONET/SDH interface. Upon receiving a standardSONET/SDH frame, the frame may be sent to the SONET/SDH descrambler 1210and overhead processor 1214 to extract the TDM data from the SONET/SDHframe. The overhead processor 1214 may send the TDM data to an H-TDMdeframer 1218. Similarly, the H-TDM frames communicated over theSONET/SDH interface may also be sent to the SONET/SDH descrambler 1210,overhead processor 1214, and H-TDM deframer 1218.

The H-TDM overlay synchronous timeslot scheme may also be received overan Ethernet interface, over multiple Ethernet interfaces that arestatistically multiplexed together, or in an encapsulated state within aplurality of Ethernet jumbo frames. Upon receiving the H-TDM overlaysynchronous timeslot scheme over an Ethernet interface or multipleEthernet interfaces, the H-TDM overlay synchronous timeslot scheme maybe sent to the H-TDM deframer 1218. Upon receiving the H-TDM overlaysynchronous timeslot scheme in a plurality of Ethernet jumbo frames, theEthernet jumbo frames may be sent to a jumbo frame deframer 1216 thatextracts the H-TDM overlay synchronous timeslot scheme. The jumbo framedeframer 1216 may then send the extracted H-TDM overlay synchronoustimeslot scheme to the H-TDM deframer 1218. The H-TDM deframer 1218 maysend the deframed timeslots to the data type demultiplexer 1220.

The data type demultiplexer 1220 may use a line card timeslot map(LT-Map) 1222 to separate the TDM, HPF, and packet data, and place theTDM, HPF, and packet data onto a TDM output, an HPF output, and a packetoutput, respectively. The data type demultiplexer 1220 may also outputthe packet data received from the 64B/66B to 9B converter 1208 to thepacket output. As shown on the packet output, the packet data maycomprise BEP data as well as high priority packet (HPP) data and circuitemulation packet (CEP) data. Persons of ordinary skill in the art willrecognize that telephonic voice data may be carried in CEPs. Each of thedifferent types of packet data may be distinguished using the optionaltag octets. A QoS demultiplexer 1224 may separate the HPP and send theHPP to a converter 1232 that converts the HPP into a HPF. Similarly, theQoS demultiplexer 1224 may optionally separate the CEP and send the CEPto a converter 1230 that converts the CEP into TDM data, which may thenbe sent to a multiplexer 1238. The QoS demultiplexer 1224 may send 9Bencoded BEP data to a 9B to 8B/10B converter 1226, which may convert the9B encoded BEP data to 8B/10B encoded BEP data. The 8B/10B encoded BEPdata may then be sent to a duplicator 1228 and output from the line card1200 over an XAUI to the Ethernet switch 1108 shown in FIG. 11.

The data type demultiplexer 1220 may send the HPF data to abuffer/groomer 1234. The buffer/groomer 1234 may also receive HPF dataconverted by the converter 1232. The buffer/groomer 1234 may perform thebuffering and data rate adaptation functions described below. The HPFdata output from the buffer/groomer 1234 may be sent to the multiplexer1238. The data type demultiplexer 1220 may output the TDM data to anoptional buffer 1236 and then to the multiplexer 1238. The multiplexer1238 may multiplex the TDM and HPF data and send the multiplexed data tothe framer 1240. The framer 1240 may send the TDM and HPF data from theline card 1200 to the SONET/SDH switch 1102 shown in FIG. 11.

The transmission path may similarly perform all of the operationsdescribed above for the reception path, but in reverse. While the linecard 1200 is shown as supporting all of the different operational modes,it is contemplated that less than all of the operational modes describedabove may be supported on the line card 1200. For example, only theH-TDM operational mode may be supported over a 10G Ethernet interface.In such a case, only the H-TDM deframer 1218 may need to be implementedon the reception path prior to the data type demultiplexer 1220.

FIG. 13 illustrates an exemplary implementation of the buffer/groomer1234. Data rate adaptation for the HPF traffic is done in a similarfashion as for traditional Ethernet data, namely by adding octets to andremoving octets from the IPG. The difference between an H-TDM link and anormal Ethernet link is that each HPF stream is transported and switchedwithin a timeslot that has a fixed bandwidth. Consequently, rateadaptation for HPF traffic may be done on a per HPF flow basis.

The principle behind rate adaptation based on IPG size manipulation isthat the packet flow, when originally created, must contain enough spacein the IPG to allow for shrinkage of the IPG due to the worst-casefrequency variations, without affecting the packet itself. The size ofthe IPG may be determined based on the size of the packet and the amountof frequency tolerance needed. The size of the IPG may also depend onthe size of the packet because adjustment opportunities for data rateadaptation only occur between packets. Otherwise, data loss may occurwhen performing the data rate adaptation. In an embodiment, the IPG mayvary in size from about two IPG octets to about twelve IPG octets.

There may be many methods for choosing the size of the IPG whenconverting HPP to HPF. One method is to determine the size of the IPG.Using a static determination, the size of the IPG may be determinedusing the largest packet size supported by the system. This method mayresult in easy and quick determinations of the IPG, but may also resultin wasted bandwidth. Another method is to determine the size of the IPGdynamically. The determination of the size of the IPG may be performeddynamically by generating an IPG that is proportional to the size of thepacket that preceded it.

As shown in FIG. 13, the buffer/groomer 1234 may receive HPF data fromthe data type demultiplexer 1220 or from the converter 1232. The HPFdata may then be multiplexed using multiplexer 1302 and sent to anend-of-packet detector and extra IPG remover 1304. Once a HPF has beengenerated from a HPP with the correct IPG, the IPG may only need to beadjusted to match the local frequency of the network on which it isbeing communicated. The IPG may be adjusted using a per flow HPF buffer1306.

Both the HPF traffic received from the demultiplexer 1220 and the HPFtraffic that may be generated by the converter 1232 may be stripped ofextra IPGs by the end-of-packet detector and extra IPG remover 1304. TheIPGs may be stripped by detecting the end of the HPF packet and removingall but one IPG octet. One IPG octet may remain between the HPF packetsto identify the boundaries of HPF packets.

When received at the ingress of the line card, the HPF packets may bewritten in the same buffer 1306 that is used when converting HPP to HPF.During that process, BEP traffic that reuses the idle HPF timeslots maybe removed, and only one idle IPG octet may be written between HPF andHPP packets. The rate adaptation may be performed while reading datafrom the buffer 1306. For traffic that was already in HPF form,additional idle octets may be inserted by an end-of-packet detector 1308between HPF packets when the buffer fill is too low. For traffic that isbeing converted from HPP to HPF, an IPG with a size determined asdescribed above may be inserted by the end-of-packet detector 1308.

As described, the rate adaptation for HPFs may be performed on the linecard 1200 shown in FIG. 12. The HPF streams are then sent in dedicatedSTS synchronous payload envelopes to the SONET/SDH switch 1102 shown inFIG. 11. From there, small granularity HPF streams may further be sentto the column switch 1106 as described above. Since these HPF flows havealready been frequency adapted, no further rate adaptation is requiredby the column switch. Consequently, the column switch 1106implementation may be simpler because the column switch 1106 maysynchronously switch all of the HPF traffic that it receives. The netresult of HPF traffic data rate adaptation using IPG manipulation in aSDH/SONET environment is that when a SDH/SONET payload varies by ±onebyte during certain high-order pointer adjustment procedures, thehigh-order pointer adjustment can be absorbed by the correspondingremoval or insertion of IPG octets.

To guarantee the QoS of the HPF flows, per-flow queuing may beimplemented using the buffer 1306 shown in FIG. 13. The per-flow queuingmay be implemented at the ingress of a node for the Ethernet packetsthat have been identified as HPP. To provide the basis for a practicalimplementation, memory access requirements may be minimized. Toaccomplish this, the conversion from HPP to HPF should take place beforethe converted HPP packets are placed in the buffer 1306 because the HPFdata is transferred on a 7B encoded timeslot basis. If the HPP packetsare stored in a manner that crosses the boundaries of the 7B-encodedstructure, multiple accesses to memory may be required, and the memoryaccess requirements would increase.

As shown in FIG. 13, the buffer 1306 may comprise a bank of buffers, andmay use one of a plurality of memory management methods. A first memorymanagement method is to have a fixed assignment of dedicated buffers.Specifically, each HPF flow may be assigned at least one dedicatedbuffer to enable the per-flow queuing. The primary issue with thismemory management method is that each buffer must be large enough tosupport the desired amount of statistical multiplexing required for theper-flow queuing because there is no reuse of buffers. Further, while nomemory may be wasted when all HPFs are equipped and active, memory maybe wasted when less than all of the HPFs are equipped and active.

In another memory management method, the buffers in the buffer 1306 maybe statically reused. In this method, the buffers that correspond tounequipped HPFs may be distributed statically among the equipped HPFs.Individual buffers may be linked together using a Buffer Link Table (notshown) to form larger buffers using the statically distributed buffers.When a new HPF is equipped, the buffer chain may need to be broken in atimely manner without affecting the service state of the existing HPFflows and without excessive delays to put the new HPF in service. Thismemory management method may be an issue if the desired buffer is beingactively used by an HPF with a slow data rate. The chain may also bereestablished without affecting the service state of the existing HPFflow.

In a further memory management method, the buffers in the buffer 1306may be dynamically reused. In this method, the buffers that correspondto unequipped HPFs may be distributed dynamically among the equippedHPFs. Again, individual buffers may be linked together using a BufferLink Table to form larger buffers using the dynamically distributedbuffers. Buffers belonging to unequipped HPFs may be pooled together asa shared resource. When an HPF requires additional memory, it may beallocated at least one additional buffer from this shared resource. Whenan HPF does not require additional buffers anymore, it may release themback to the pool. The timely release of the shared buffer could be anissue if the HPF goes idle while using a shared buffer.

In a final memory management method, the buffers in the buffer 1306 maybe dynamically assigned. In this method, all of the buffers in buffer1306 may be dynamically distributed among the equipped HPFs. Individualbuffers may be linked together using a Buffer Link Table to form largerbuffers. HPF QoS may be guaranteed in one of at least three methods. Afirst method to guarantee QoS may be to assign a minimum quantity ofbuffers to each HPF using a sliding window method. That is, each time aHPF releases a buffer, it is assigned another buffer if the HPF is belowits minimum quantity of buffers. A second method to guarantee QoS may beto assign a maximum number of buffers to each HPF. The sum of thesemaximum buffer numbers should not exceed the amount of buffersavailable. A third method to guarantee QoS may be to implement acombination of the first and second methods of guaranteeing QoS. When anHPF requires additional memory, it may be allocated at least oneadditional buffer from the non-assigned buffer pool. When the HPF doesnot require these additional buffers anymore, it releases them back tothe pool. The third method may be advantageous in that the chain doesnot have to be closed. A virtual buffer may be created by continuouslylinking new physical buffers together.

FIG. 14 illustrates another embodiment of a multi-transport switch 1400similar to the multi-transport switch 1100 described above. Themulti-transport switch 1400 comprises a dual-mode switching fabriccomprising a SONET/SDH switch 1418 and an Ethernet switch 1420. Themulti-transport switch 1400 also comprises a plurality of backplaneinterconnects that maintain a pseudo-SONET/SDH architecture. Themulti-transport switch 1400 supports TDM line card 1110 and the Ethernetline card 1112 described above, and the H-TDM line cards 1410, 1412,1416, which are similar to the H-TDM line cards 1114, 1116, and 1118.However, the H-TDM line cards 1410, 1412, and 1416 differ from the H-TDMline cards 1114, 1116, and 1118 in that the H-TDM line cards 1114, 1116,and 1118 do not use the SONET/SDH switch 1418 to exchange TDM, HPF, andBEP data with the switching fabric.

The multi-transport switch 1400 also comprises a data type demultiplexer1402 and a data type multiplexer 1406. The data type demultiplexer 1402uses an ingress fabric timeslot map (FT-Map) 1404 to separate the HPFand TDM data from the BEP data. The HPF and TDM data may be sent to theSONET/SDH switch 1418, while the BEP data is sent to the Ethernet switch1108. The BEP data may undergo clock domain adaptation before being sentto the Ethernet switch 1420 if the Ethernet switch 1420 operates at adifferent base frequency than the SONET/SDH switch 1418. After beingswitched by the SONET/SDH switch 1418 and Ethernet switch 1420, the HPF,TDM, and BEP data is sent to the data type multiplexer 1404, which usesan egress FT-Map 1408 to multiplex the TDM and HPF data with the BEPdata. The data type multiplexer 1406 may perform clock domain adaptationon the BEP data. The data type multiplexer 1406 may then send themultiplexed TDM, HPF, and BEP data to one of the H-TDM line cards 1410,1412, or 1414.

FIG. 15 illustrates an exemplary functional block diagram of an H-TDMline card 1500 that may be one of the H-TDM line cards 1114, 1116, or1118. The H-TDM line card 1500 may be structured and may operatesimilarly to the H-TDM line card 1200 described above. However, theH-TDM line card 1500 may differ from the H-TDM line card 1200 at theoutput of the reception path and the input of the transmission path.Specifically, rather than outputting the TDM and HPF data separatelyfrom the BEP data, the HPF, TDM, and BEP data may all be output togetheron a common reception path. In such an embodiment, a data typemultiplexer 1502 may use an ingress backplane timeslot map (BT-Map) 1504to multiplex the TDM, HPF, and BEP data together. The multiplexed datamay then be sent to a data path/type duplicator and framer 1506 andcommunicated to the data type demultiplexer 1402 shown in FIG. 14. Thedata type multiplexer 1502 may also perform clock domain adaptation toadapt the Ethernet line interface data rates to the data rates of thetelecommunication bus connecting the line card 1500 to the data typedemultiplexer 1402. As with the line card shown in FIG. 12, thetransmission path may similarly perform all of the operations describedabove for the reception path, but in reverse.

FIG. 16 illustrates an exemplary multi-transport switch 1600 thatsupports the switching of the H-TDM overlay synchronous timeslot scheme.The multi-transport switch 1600 is similar to the multi-transport switch1400 described above, except there is no support for legacy Ethernet orSONET/SDH line cards. In addition, the TDM, HPF, and BEP data may besent to the switching fabric over XAUI interfaces using 8B/10B encoding.The multi-transport switch 1600 is centered on a dual-mode switch fabricsimilar to that described above. The dual-mode switch fabric supportsTDM and HPF switching via a SONET/SDH switch 1628 and BEP switching viaan Ethernet switch 1626.

The multi-transport switch 1600 has a switching fabric that comprises adata path multiplexer 1602, a data type demultiplexer 1604, a data pathdemultiplexer 1608, and a data type multiplexer 1610. The data pathmultiplexer 1602 multiplexes the 8B/10B encoded TDM, HPF, and BEP datafrom a plurality of H-TDM line cards 1618, 1620, 1622, and 1624. Themultiplexed data may then be sent to the data type demultiplexer 1604,which separates the 8B/10B encoded TDM and HPF data from the BEP datausing an ingress FT-Map 1606. The BEP data may then be sent to thestandard Ethernet switch 1626, while TDM and HPF data may be sent to aclock adaptor and column groomer 1614. The clock adaptor and columngroomer 1614 may convert the TDM and HPF data from the 8B/10B encodingscheme to the 8B encoding scheme. Further, the clock adaptor and columngroomer 1614 may work in conjunction with a column switch 1630 and theSONET/SDH switch 1628 to switch of HPF and VT-based TDM traffic.

The multi-transport switch also comprises a clock adaptor 1616 thatconverts the 8B encoded TDM and HPF data received from the SONET/SDHswitch 1628 into 8B/10B encoded TDM and HPF data. The 8B/10B encoded TDMand HPF data may be sent to the data type multiplexer 1610 along withBEP data received from the Ethernet switch. The data type multiplexer1610 uses an Egress FT-Map 1612 to multiplex the TDM, HPF, and BEP datatogether in accordance with the H-TDM overlay synchronous timeslotscheme. The multiplexed TDM, HPF, and BEP data may then be sent to thedata path demultiplexer 1608, where it is then distributed to the H-TDMline cards 1618, 1620, 1622, and 1624.

FIG. 17 illustrates an exemplary multi-transport switch 1700 thatswitches on the H-TDM overlay synchronous timeslot scheme. Themulti-transport switch 1700 is similar to the multi-transport switch1600 described above, except that the multi-transport switch 1700switches the TDM and HPF data using a full column switch 1702. The fullcolumn switch prevents the HPF flows from being blocked and eliminatesgrooming complexities. The SONET/SDH overhead processing functions maybe performed on SONET/SDH line cards coupled to the multi-transportswitch 1700, thereby minimizing the amount of legacy functionality thathas to be implemented in the multi-transport switch 1700 to supporttraditional TDM traffic. Some exemplary implementations of the H-TDMline cards 1618, 1620, 1622, and 1624 follow.

FIG. 18 illustrates an exemplary functional block diagram of the H-TDMline card 1800, which may be the H-TDM line cards 1618 and 1620described above. The H-TDM line cards 1800 may be structured similar tothe H-TDM line cards described above, but may receive data over aSONET/SDH interface. The H-TDM line card 1800 may differ from the H-TDMline cards describe above in that the HPF and TDM data are encoded usingthe 8B/10B encoding scheme. Specifically, the 8B encoded TDM data andthe 7B encoded HPF data are converted to the 8B/10B (10B) encodingscheme using a converter 1802 on the reception path. Further, the H-TDMline card 1800 comprises an extractor 1804 that extracts packet datathat has been encapsulated in a SONET/SDH frame in accordance withGFP/LAPS and transported over the SONET/SDH interface. This packet datamay comprise low priority BEP packet data and high priority packet data.The H-TDM line card 1800 may optionally comprise a QoS demultiplexer1806 that separates the low priority BEP data from the high prioritypacket data. The high priority packet data may then be converted intoTDM or HPF data using a converter 1810. The transmission path maysimilarly be modified.

FIG. 19 illustrates an exemplary functional block diagram of the H-TDMline card 1900, which may be the H-TDM line card 1622 described above.The H-TDM line card 1900 may be structured similar to the H-TDM linecards 1618 and 1620 described above, but may receive data over a 10GEthernet interface. The H-TDM line card 1622 differs from the H-TDM linecards described above in that the extractor is replaced by a converter1902. The converter 1902 converts the 64B/66B encoded Ethernet data into8B/10B encoded Ethernet data. A similar converter also exists on thetransmission path.

FIG. 20 illustrates an exemplary functional block diagram of the H-TDMline card 2000, which may be the H-TDM line card 1624 described above.The H-TDM line card 2000 may be structured similar to the H-TDM linecards 1618 and 1620 described above, but may receive data over aplurality of Ethernet interfaces. The H-TDM line card 2000 differs fromthese H-TDM line cards in that the plurality of Ethernet interfaces allfeed into a data path multiplexer 2002 before being communicated to theswitching fabric of the multi-transport switch. Similarly, the H-TDMline card 2000 comprises a data path demultiplexer 2004 that separatesdata received from the switching fabric of the multi-transport switchand communicates the data over the plurality of Ethernet interfaces.

FIG. 21 illustrates an exemplary unified network 2100 that may transportTDM and packet data over SONET/SDH and Ethernet interfaces. The unifiednetwork 2100 comprises a legacy switch 2122 and a plurality ofmulti-transport switches 2102, 2104, 2106, 2108, 2110, 2112, 2114, 2116,2118, 2120 (collectively, 2102-2120), which may be the multi-transportswitches described herein. As such, the multi-transport switches2102-2120 may communicate with each other and the legacy switch 2122using an Ethernet, SONET, or SDH protocol, or the H-SYNC, H-TDM, orH-JUMBO operational modes described above.

In the specific embodiment shown in FIG. 21, the solid lines mayrepresent Ethernet links and the dashed lines may represent a SONET/SDHlinks. The communications links are shown with arrows pointing in bothdirections to represent bi-directional full-duplex communication. In anembodiment, at least some of the multi-transport switches 2102-2120and/or the legacy switch 2122 may support half-duplex communication. Theinterface between the links and the multi-transport switches 2102-2120may represent the interface between a physical communication medium andthe line cards on the multi-transport switches 2102-2120. For example,the interface of the solid line with that of the multi-transportswitches 2102-2120 may represent an Ethernet line card that sends andreceives data over the Ethernet link. As shown in FIG. 21, themulti-transport switches 2102-2120 are depicted with at least two links,thus the multi-transport switches 2102-2120 may contain at least twoline cards. In an embodiment, at least one of the multi-transportswitches 2102-2120 may implement a single line card with multiple ports.The multi-transport switches 2102-2120 may utilize at least one of theline cards depicted in FIGS. 12-20 and/or at least one of legacySONET/SDH or Ethernet line cards.

Some of the multi-transport switches 2102-2120 may support the mappingof TDM, HPF, and BEP data from the Ethernet links to the SONET/SDHlinks, or vice versa. For example, the multi-transport switch 2102 mayreceive data over the Ethernet link and map the data to SONET so thatthe data may be transported over the SONET/SDH link to themulti-transport switch 2118. The data may be mapped between protocolsand/or operational modes multiple times when traversing the unifiednetwork 2100. For example, the multi-transport switch 2102 may send dataover the Ethernet link to the multi-transport switch 2104, which maythen map the data to SONET so that the data may be transported over theSONET/SDH link to the multi-transport switch 2112. The multi-transportswitch 2112 may then map the data back to Ethernet so that the data maybe transported over another Ethernet link.

The multi-transport switches 2102-2120 may also support communicationwith the legacy switch 2122. For example, the legacy switch 2122 may bea legacy Ethernet switch, and the multi-transport switch 2102 maycommunicate with the legacy switch 2122 over an Ethernet link using astandard Ethernet protocol or the H-SYNC or H-JUMBO operational modes.Alternatively, the legacy switch 2122 may be a legacy SONET/SDH switchand the multi-transport switch 2102 may communicate with the legacyswitch 2122 over a SONET/SDH link. In such a case, the multi-transportswitch 2102 may communicate TDM and HPF data using the H-TDM operationalmode, or the multi-transport switch 2102 may communicate packet datausing standard Ethernet communications or the H-SYNC operational modeusing the WIS. While only one legacy switch 2122 is shown, it iscontemplated that the unified network 2100 may comprise a plurality oflegacy switches 2122 distributed throughout the unified network 2100.

The unified network 2100 may be used as a backbone network, an accessnetwork, or any other network or portion of a network. As such, theunified network 2100 may have some of the multi-transport switches2102-2120 on the edge of the network and some of the multi-transportswitches 2102-2120 within the core of the network. The multi-transportswitches 2102-2120 within the core of the network may communicate withother multi-transport switches 2102-2120 or other legacy switches 2122to facilitate data transport across the network.

The multi-transport switches 2102-2120 may communicate with variousdevices that need to send and receive data, such as service providersand service users. For example, the multi-transport switches 2108, 2110,2112, 2114, 2116, 2118, 2120 (collectively, 2108-2120) may also be onthe edge of the network, and the multi-transport switches 2104, 2106,2112 may be at the core. The multi-transport switch 2102 may receiveTDM, HPF, and BEP data over the Ethernet link and/or the SONET/SDH linkfrom at least one data source, which may be a service provider or anyother data originator. The multi-transport switches 2108-2120 may senddata to the data user, which may be a service user.

Recall that the H-TDM and the H-SYNC operational modes enablesynchronized communication. Further, while the H-SYNC operational modemay enable frequency-synchronized communication, the H-TDM operationalmode enables both frequency-synchronized and phase-alignedcommunication. Specifically, the synchronization windows on two or moreof the multi-transport switches 2102-2120, delineated by the internalsynchronization signal described above, may have the same period, andthus may be frequency-synchronized. The internal synchronization signalmay happen at the same time on two or more of the multi-transportswitches 2102-2120, such that the synchronization windows on two or moreof the multi-transport switches 2102-2120 occur during the same absolutetime, referred to as phase-alignment. In an embodiment, themulti-transport switches 2102-2120 may be frequency-synchronized andphase-aligned when implementing the H-TDM operational mode.

The H-TDM operational mode may frequency-synchronize and phase-align themulti-transport switches 2102-2120 by calculating and adjusting for thecommunication delay between the multi-transport switches 2102-2120. Asshown in FIG. 21, there are intervening nodes between some of themulti-transport switches 2102-2120. For example, multi-transport switch2104 is an intervening node between the multi-transport switch 2102 andthe multi-transport switch 2110. On the other hand, there are nointervening nodes between the multi-transport switch 2102 and themulti-transport switch 2108. Further, some intervening nodes may belegacy switches, such as the legacy Ethernet switch 2122, and some maybe multi-transport switches, such as multi-transport switch 2104. Assuch, with the varying numbers and types of intervening nodes along thecommunication pathways between the multi-transport switches 2102-2120there may be differing delays along each communication pathway.

In some instances, it may be desirable to communicate synchronouslybetween the multi-transport switch 2102 and two or more of themulti-transport switches 2108-2118 using the H-TDM operational mode.Specifically, the H-TDM operational mode allows the multi-transportswitches 2108-2118 to establish at least one synchronous communicationpathway. For example, the multi-transport switch 2102 may be configuredto receive multimedia content from a multimedia distributor, which maybe multicast over a plurality of communication pathways to the two ormore of the multi-transport switches 2108-2118. The multi-transportswitches 2108-2118 may then distribute the multimedia content to aplurality of subscribers. By taking into account the different delaysalong the communication pathways, the multi-transport switch 2102 maycompensate for the delay along each communication pathway such that themultimedia content may arrive substantially simultaneously at each ofthe two or more multi-transport switches 2108-2118. This may bedesirable when synchronizing the playback of multimedia content betweenseveral multimedia content subscribers, or having a conference callbetween a plurality of remote parties.

While the above example was directed to the distribution and playback ofmultimedia content, persons of ordinary skill in the art will recognizethat the delayed distribution and synchronized reception of data atdifferent locations may be used with any data type. Further, while theabove example was directed to distributing data from one source to aplurality of locations, persons of ordinary skill in the art willappreciate that multiple data sources may have their data synchronouslyreceived at a single location. For example, each musician in a band maybe remotely located while having a recording session at a remoterecording studio. In this example, the music produced by each musicianmay be synchronized together to be recorded at the remote recordingstudio. Many other applications that have already been envisioned andhave yet to be envisioned are enabled through synchronized communicationin the unified network 2100.

FIG. 22 illustrates an exemplary network architecture 2200 forcommunicating TDM, HPF, and BEP data. The network architecture 2200comprises a plurality of service providers or data producers 2202, 2204,2206 (collectively, 2202-2206), at least one multi-transport switch 2208that may act as a backbone network, at least one multi-transportmultiplexer 2210 that may act as an access network, and a plurality ofservice users or data consumers 2214. The data producers 2202-2206 maybe HPF data producers 2202, TDM data producers 2204, and/or BEP dataproducers 2206. Persons of ordinary skill in the art will recognize thateach of the data producers 2202-2206 may also receive data, such asrequests for data or services or back channel information from consumerdevices. The HPF data producers 2202 may comprise an audio/video (A/V)server, a broadcast multimedia distributor, an interactive multimediadistributor, a multimedia distribution network, a real-time serviceprovider, and a utilities/disaster manager. The TDM data producers 2204may comprise the public switched telephone network (PSTN), a centraloffice coupled to the PSTN, or a cellular telephone network. The BEPdata producers 2206 may comprise a wide area network (WAN), a local areanetwork (LAN), a metro area network (MAN), an intranet, the internet, aninternet service provider, a wireless access point, or a web server.

While some examples of the data producers 2202-2206 are described above,these are merely exemplary lists and do not exhaustively describe all ofthe data producers 2202-2206. Further, while each of the data producersdescribed above is categorized by the data type they produce, it iscontemplated that some data producers may be categorized under two ormore data types. For example, an interactive multimedia distributor maytransmit multimedia data as BEP data in situations when a multimediapresentation is not intended for immediate playback, but is ratherdownloaded to a consumer device, such as a set top box, to be playedback later. The same interactive multimedia distributor may alsotransmit HPF data when the multimedia data is meant to be viewedsubstantially in real-time.

The backbone network of the network architecture 2200, including atleast one multi-transport switch 2208, may be coupled to each of thedata producers 2202-2206 through at least one Ethernet or SONET/SDHlink. Similar to the unified network 2100 in FIG. 21, the solid linesrepresent Ethernet links and the dashed lines represent SONET/SDH links.For example, the multi-transport switch 2208 may be coupled to the ANserver though an Ethernet link, and may be coupled to a central officeor the PSTN through a SONET/SDH link. The multi-transport switch 2208may be coupled to the TDM-based networks without a media gateway becausethe multi-transport switch 2208 may be able to communicate TDM data inits native mode over both SONET/SDH interfaces and Ethernet interfaces.As such, the TDM data does not need to be buffered, encapsulated, orotherwise modified prior to communication by the multi-transport switch2208. The multi-transport switch 2208 may be one of the multi-transportswitches described above. Further, the multi-transport switch 2208 maycomprise a plurality of multi-transport switches arranged as the unifiednetwork described above. As such, the multi-transport switch 2208 maycommunicate the TDM, HPF, and BEP data over the backbone network to themulti-transport multiplexer 2210, or directly to the data consumers2214.

As mentioned above, the multi-transport multiplexer 2210 may act as anaccess network in the network architecture 2200. As such, themulti-transport multiplexer 2210 may provide the “last mile”communication to the data consumers 2214. For example, themulti-transport multiplexer 2210 may communicate with the data consumers2214 via an Ethernet link, or using other conventional “last mile”technologies such as communicating over a wireless network 2212, atwisted wire pair, a coaxial cable, a passive optical network, orfiber-to-home. In an embodiment, the multi-transport multiplexer 2210may be part of or used in conjunction with an access provider.

The data consumers 2214 may be any residential, business, or mobiledevice customer or service user. Persons of ordinary skill in the artwill recognize that the data consumers 2214 may also produce data suchas documents, spreadsheets, pictures, movies, and other data that may besent to other data consumers 2214 and/or the data producers 2202-2206.The data consumers may comprise a WAN interface 2216 that communicateswith a plurality of consumer networks and devices. Specifically, theconsumer networks and devices may comprise a private wireless network2218, a private wired network 2220, and a plurality of consumer devices2222, such as a laptop computer, a cellular telephone, and a television.Further, the WAN interface 2216 may enable communication with locallyimplemented services at the consumer's location, such as securityservices 2224, utilizes management 2226, and emergency services 2228.

The system described above may be implemented on any general-purposecomputer with sufficient processing power, memory resources, and networkthroughput capability to handle the necessary workload placed upon it.FIG. 23 illustrates a typical, general-purpose computer system suitablefor implementing at least one embodiment disclosed herein. The computersystem 2380 comprises a processor 2382 (which may be referred to as acentral processor unit or CPU) that may be in communication with memorydevices including secondary storage 2384, read only memory (ROM) 2386,random access memory (RAM) 2388, input/output (I/O) devices 2390, andnetwork connectivity devices 2392. The processor 2382 may be at leastone CPU chip.

The secondary storage 2384 may typically be comprised of at least onedisk drive or tape drive and may be used for non-volatile storage ofdata and as an over-flow data storage device if RAM 2388 is not largeenough to hold all working data. Secondary storage 2384 may be used tostore programs which are loaded into RAM 2388 when such programs areselected for execution. The ROM 2386 may be used to store instructionsand perhaps data which are read during program execution. ROM 2386 maybe a non-volatile memory device which typically has a small memorycapacity relative to the larger memory capacity of secondary storage2384. The RAM 2388 may be used to store volatile data and perhaps tostore instructions. Access to both ROM 2386 and RAM 2388 is typicallyfaster than to secondary storage 2384.

I/O devices 2390 may comprise printers, video monitors, liquid crystaldisplays (LCDs), touch screen displays, keyboards, keypads, switches,dials, mice, track balls, voice recognizers, card readers, paper tapereaders, or other well-known input devices. The network connectivitydevices 2392 may take the form of modems, modem banks, Ethernet cards,universal serial bus (USB) interface cards, serial interfaces, tokenring cards, fiber distributed data interface (FDDI) cards, wirelesslocal area network (WLAN) cards, radio transceiver cards such as codedivision multiple access (CDMA) and/or global system for mobilecommunications (GSM) radio transceiver cards, and other well-knownnetwork devices. These network connectivity devices 2392 may enable theprocessor 2382 to communicate with an Internet or at least one intranet.With such a network connection, it is contemplated that the processor2382 might receive information from the network, or might outputinformation to the network in the course of performing theabove-described method steps. Such information, which is oftenrepresented as a sequence of instructions to be executed using processor2382, may be received from and outputted to the network, for example, inthe form of a computer data signal embodied in a carrier wave.

Such information, which may comprise data or instructions to be executedusing processor 2382, for example, may be received from and outputted tothe network, for example, in the form of a computer data baseband signalor signal embodied in a carrier wave. The baseband signal or signalembodied in the carrier wave generated by the network connectivitydevices 2392 may propagate in or on the surface of electricalconductors, in coaxial cables, in waveguides, in optical media, forexample optical fiber, or in the air or free space. The informationcontained in the baseband signal or signal embedded in the carrier wavemay be ordered according to different sequences, as may be desirable foreither processing or generating the information or transmitting orreceiving the information. The baseband signal or signal embedded in thecarrier wave, or other types of signals currently used or hereafterdeveloped, referred to herein as the transmission medium, may begenerated according to several methods well known to persons of ordinaryskill in the art.

The processor 2382 executes instructions, codes, computer programs,scripts which it accesses from hard disk, floppy disk, optical disk(these various disk based systems may all be considered secondarystorage 2384), ROM 2386, RAM 2388, or the network connectivity devices2392.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods might beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented. In addition,persons of ordinary skill in the art will appreciate that the term octetas used herein is synonymous with the term byte, and that the octetsdescribed herein do not necessarily have to contain eight bits.

In addition, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by persons of ordinaryskill in the art and could be made without departing from the spirit andscope disclosed herein.

1. A network comprising: a first line card configured to send a datastream via an Ethernet interface, wherein the data stream comprises anEthernet packet data and a time division multiplexed (TDM) data; asecond line card configured to receive the data stream via the Ethernetinterface; a third line card configured to send the data stream via aSONET/SDH interface; and a fourth line card configured to receive thedata stream via the SONET/SDH interface, wherein the first line card,the second line card, the third line card, and the fourth line card aresynchronized to an absolute time.
 2. The network of claim 1, wherein thesecond line card and the fourth line card are phase-aligned.
 3. Thenetwork of claim 1, further comprising: a fifth line card configured toreceive the data stream from the second line card via the Ethernetinterface and send the data stream via a second SONET/SDH interface; aswitch configured to receive the data stream from the fifth line cardvia the second SONET/SDH interface, process the data stream, and sendthe data stream via a third SONET/SDH interface; and a sixth line cardconfigured to receive the data stream from the switch via the thirdSONET/SDH interface and send the data stream via a second Ethernetinterface, wherein the fifth line card, the switch, and the sixth linecard, are located between the first line card and the second line card.4. The network of claim 3, further comprising: a seventh line cardconfigured to receive the data stream from the switch via a fourthSONET/SDH Ethernet interface; and an eighth line card configured toreceive the data stream from the seventh line card via fifth SONET/SDHinterface, wherein the seventh line card is located between the switchand the eighth line card, wherein the eighth line card is synchronizedto an absolute time, and wherein the reception of the data stream at thesecond line card, the fourth line card, the sixth line card and theeighth line card are phase-aligned.
 5. The network of claim 1, whereinthe data stream further comprises high priority flow data and at leastone idle bit subsequent to the high priority flow, wherein a quantity ofidle bits is adjusted according to a size of a SONET/SDH payload.
 6. Thenetwork of claim 1, wherein the Ethernet packet data comprises a besteffort packet (BEP) data and a high performance flow (HPF) data.
 7. Thenetwork of claim 6, wherein the first line card, the second line card,the third line card, and the fourth line card each comprise a data typemultiplexer, wherein the data type multiplexer multiplexes the Ethernetpacket data and the TDM data on a common data path.
 8. The network ofclaim 7, wherein the data type multiplexer maps the location of the BEPdata, the HPF data, and the TDM data using a timeslot map.
 9. Thenetwork of claim 8, wherein the timeslot map is transmitted with themultiplexed data.
 10. The network of claim 7, wherein the data typemultiplexer is configured to perform clock domain adaptation.
 11. Amethod comprising: sending, by a first line card, a data stream via anEthernet interface, wherein the data stream comprises an Ethernet packetdata and a time division multiplexed data; receiving, by a second linecard, the data stream via the Ethernet interface; sending, by a thirdline card, the data stream via a SONET/SDH interface; and receiving, bya fourth line card, the data stream via the SONET/SDH interface,synchronizing the first line card, the second line card, the third linecard, and the fourth line card to an absolute time.
 12. The method ofclaim 11, further comprising: phase-aligning the second line card andthe fourth line card.
 13. The method of claim 11, further comprising:receiving, by a fifth line card, the data stream from the second linecard via the Ethernet interface; sending, by the fifth line card, thedata stream via a second SONET/SDH interface; receiving, by a switch,the data stream from the fifth line card via the second SONET/SDHinterface; process, by the switch, the data stream; sending theprocessed data stream via a third SONET/SDH interface; and receiving, bya sixth line card, the data stream from the switch via the thirdSONET/SDH interface; and sending the data stream via a second Ethernetinterface, wherein the fifth line card, the switch, and the sixth linecard, are located between the first line card and the second line card.14. The method of claim 13, further comprising: receiving, by a seventhline card, the data stream from the switch via a fourth SONET/SDHEthernet interface; receiving, by an eighth line card, the data streamfrom the seventh line card via a fifth SONET/SDH interface;synchronizing the eighth line card to an absolute time; andphase-aligning the reception of the data stream at the second line card,the fourth line card, the sixth line card and the eighth line card,wherein the seventh line card is located between the switch and theeighth line card.
 15. The method of claim 11, further comprising:adjusting a quantity of idle bits according to a size of a SONET/SDHpayload, wherein the data stream further comprises high priority flowdata and at least one of the idle bits subsequent to the high priorityflow.
 16. The method of claim 11, wherein the Ethernet packet datacomprises a best effort packet (BEP) data and a high performance flow(HPF) data.
 17. The method of claim 16, further comprising multiplexing,by a data type multiplexer, the Ethernet packet data and the TDM data ona common data path, wherein the first line card, the second line card,the third line card, and the fourth line card each comprise a data typemultiplexer.
 18. The method of claim 17, further comprising: mapping, bythe data type multiplexer, the location of the BEP data, the HPF data,and the TDM data using a timeslot map.
 19. The method of claim 18,further comprising: transmitting the timeslot map with the multiplexeddata.
 20. The method of claim 17, further comprising: performing, by thedata type multiplexer, clock domain adaptation.